last update
February 7, 2011
MANUAL
UTI Evaluation board
reference
uti toolkitn.doc
page
1/8
Universal Transducer Interface (UTI)
Evaluation Board
1.
Introduction
page 2
2.
Operating the UTI evaluation board
page 4
3.
Connections and connectors
page 4
4.
Running the UTI interfacing software
page 6
5.
OnOn-board reprogramming
page 7
6.
Multiple
Multiplele -capacitance measurement
page 8
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
2/8
1. Introduction
This Application Note describes an evaluation board for the UTI. The UTI is a complete front-end
interface for many types of passive sensors, such as resistive, resistive-bridge and capacitive
sensors. The UTI converts low-level sensor signals to a period-modulated microcontroller-compatible
signal. By the application of continuous auto-calibration a high accuracy, of up to 13 bits, is
obtained. Full data of the UTI is available in the UTI specification sheet and should be consulted in
conjunction with this Application Note when using the Evaluation Board.
The evaluation board is equipped with a microcontroller (Microchip PIC16C73A). An RS232
interfacing chip offers serial communication between the microcontroller and, for instance, a
personal computer. A 20 MHz crystal completes the on-chip oscillator of the microcontroller. Two
voltage regulators (78L05) provide the 5 V, DC supply voltages for the UTI, and the microcontroller
and the RS232 interfacing, respectively.
The evaluation-board block diagram is shown in Figure 1, while a full circuit diagram and a
photograph of the evaluation board are shown in Figure 2 and Figure 3, respectively.
J4 ICD
J3
VDD
Voltage regulator
+5V
A
A′
F UTI
E
B
C
D
J2
P8
Voltage regulator
A
µC
RS232
CLR
SCK
DATA
P7
J1
Figure 1 Functional block diagram.
9-way
D-type
connector
J5
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
3/8
PIC16C73
U2
C7
10
4.7p
OSC2/CLKOUT
9
OSC1/CLKIN
RA1/AN1
U3
4
5
SEL1
9
3
2
D 1
E 15
F 14
A
SEL2
B
C
SEL3
SEL4
6
7
RC0/T1OSO/T1CKI
13
RC2/CCP1
RC3/SCK/SCL
SYNC
14
15
16
TxD
RxD
17
RB5
RB4
RA5
RB1
11
12
RC1/T10SI/CCP2
18
RB0/INT
RB1
RB2
RC4/SDI/SDA
RC5/SDO
RB3
RB4
RC6/TX/CK
RC7/RX/DT
RB5
RB6
D
E
TEST
F
OUT
PD
13
12
SF
RA3
11
OUT
RB2
10
RB0
1
C1+
V+
21
RB0
22
RB1
RB2
24
25
RB3
26
RB5
RB6
1.0
3
C1-
V-
4
C2+
5
C2-
11
T1IN
T1OUT
14
6
10
T2IN
T2OUT
7
2
7
12
R1OUT
R2OUT
13
3
8
8
C20
P7
TxD
RxD
9
RB7
RB7
RB6
6
VCC
5
4
ICD
3
2
BNC
Sync Pulse
VCC
GND
CON6
OUT
Output
VCC
J2
VDD
D
C
B
E
F
A1
U5
5
7
6
8
9
10
GND
GND
GND
11
13
15
12
14
16
1
C11
100.0
C10
D2
C13
P8
Vin
8
IN
0.1
G
N
D
C1
0.1
100.0
POWER
2
VCC
GND
GND
VDD
CON16A
J1
VDD
78L05
VDD
SCK
GND
U4
D
1
3
2
4
GND
C
B
5
6
F
A1
11
13
8
10
12
C
B
E
7
9
A1
15
D
1
C9
C8
78L05
VDD
C16
IN
R1
R
C12
8
D1
LED
G
N
D
E
14
F
A1
16
A
4
9
5
DB9
SYNC
RB3
MCLR
1
DATA
R1IN
R2IN
J4
R2
J3
2
4
1.0
1
MAX232
10K
1
3
6
RB4
27
28
UTI
CLR
VCC
C18
1.0
MCLR/VPP
MCLR
A
SCK
CLR
DATA
23
RB7
1.0
2
1
C19
RA3
2
RA0/AN0
OUT
OUT
B
C
5
4
3
RA2/AN2
C4
RA5
RA4
6
RA3/AN3/VR
4.7p
A
U1
7
RA5/AN4/SS
RA4/TOCI
Q1
20M
C17
2
10.0
0.1
0.1
0.1
CON16A
Figure 2 Circuit diagram of the UTI evaluation board.
6-point solder
pads (J4)
16-point solder
pads (J1)
D-type
connector
(P7)
16-point
solder pad
array (J2)
1
5-point
solder pads
(J3)
Power supply
connector (P8)
1
3-pin header (J5)
Figure 3 A photograph of the UTI evaluation board.
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
4/8
2. Operating the UTI evaluation board
Functions
The evaluation board can be used for all functions of the UTI. The setting of the operating mode is
performed by the microcontroller. Moreover, the microcontroller also measures the output signal
from UTI and communicates with the outside digital world.
Power supply
Two on-board voltage regulators (78L05) provide the internal supply voltages of 5 V. The board
requires an external DC supply voltage in the range of 7 V to 15 V.
3. Connections to the board
Evaluation board interfacing
Connection to the UTI evaluation board is implemented with six connectors/connecting pads:
J2
16-point solder pad array for connection of the sensing, reference and biasing elements
J3
5-point solder pads for connection of capacitive sensing elements
J4
6-point solder pads for connection to the ICD reprogramming module
J5
3-pin header to monitor UTI with an oscilloscope
P7
9-way D-type connector for communication with a PC (standard serial cable)
P8
Socket for connection of power supply
Figures 4, 5, 6, 7 & 8 show the pin/pad connections.
The soldering-pad arrays, J2 and J3, are used for mounting flat cable wires, sockets, or external
components. This enables the connection of to connect external sensing, reference and biasing
elements. In the CMUX mode of the UTI, the on-board microcontroller provides the control signals
(CLR, DATA and SCK) for an optional, external multiplexer, via the soldering pad J2. For detailed
information about the CMUX mode, please consult the UTI specification sheet.
In the capacitive modes of the UTI the measurement system is very sensitive to signals that are
capacitively coupled with the input A, including capacitive-coupled interference signals. To provide
selective detection of the desired signals only, for the connection to input A, a shielded or coaxial
cable wire must be used. For this purpose pad J3 provides a connection for a coaxial plug. In other
UTI modes, it is allowed to connect input node A using unshielded wire. In these modes, a wired
connection is made between the soldering pads A′ and A′′ (Figure 1). For the connections of various
sensors, it is advised to consult the UTI specification sheet. The order of the J2 soldering pad array
is shown in Figure 4.
The output signal of the UTI can be monitored, using an oscilloscope, connected via header J5
(Figure 6). Besides the output signal this header also provides a trigger signal for the oscilloscope.
The soldering pads are also used to mount the required external reference and biasing components.
These components are chosen in accordance with the UTI mode. For instance, in the Pt100 mode
of the UTI, the user has to connect a current-limiting resistor RBIAS and a reference resistor Rref, using
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
5/8
soldering pad J2. For the other modes, please consult the UTI specification sheet. WhenJ3 is not
used, pads A to A’ of pad array J2 have to be connected by wire.
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
1 to 6
7
8
9
10
11
12
13
14
15
16
GND
SCK
DATA
CLR
VDD
D
C
B
E
F
A’
Evaluation-board ground
For MUX use
For MUX use
For MUX use
Power supply
Sensors connection of UTI
Sensors connection of UTI
Sensors connection of UTI
Sensors connection of UTI
Sensors connection of UTI
Sensors connection of UTI
Figure 4 J2 pad configuration.
1
1
2
3
4
5
6
2
3
4
5
Evaluation-board ground
+5 V Power supply output
MCLR
RB3
RB6
RB7
6
J4
Figure 5 J4 pin configuration.
1
2
3
1
2
Evaluation-board ground
Trigger signal
Output signal of UTI
3
J5
Figure 6 J5 pin configuration.
5
9
4
8
3
7
2
6
1
2
3
4
5
6
7
8
9
1
Figure 7 P7 pin configuration.
NC
T1OUT
R1IN
NC
GND
NC
NC
NC
NC
Not connected
Serial data input
Serial data output
Not connected
Evaluation-board ground
Not connected
Not connected
Not connected
Not connected
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
6/8
1
2
1 Power supply
2 Evaluation-board ground
P8
Figure 8 P8 pin configuration.
4. Running the UTI interfacing software
There are many ways to display evaluated results, such as the terminal program under Windows and
the LabView program. The following shows two of them.
4.1 Executable LabView
Included in the UTI development kit is a PC-compatible disk, which contains the software for
controlling and evaluating the performance of the UTI using the serial port of a PC. There are three
files, named: EVAL-UTI.arj, ARJ.exe and SERPDRV, respectively, on the contribution disk. The file
SERPDRV is a serial-port-driver file. The file EVAL-UTI.arj is a freshened file of EVAL-UTI.exe, and
ARJ.exe is a file manager.
To use the software, the user must have an IBM-compatible PC, with Windows 95 or later installed.
These three files on the contribution disk have to be copied to a subdirectory, for instance, EVALUTI, in the hard disk of your PC. After that, the EVAL-UTI.arj should be extracted by running ARJ.exe
under DOS or Windows. This can be performed by running arj e evaleval -uti.arj. Then, the file EVALUTI.exe is extracted.
When working under Windows and using the FILE MANAGER you can simply double click on EVALUTI.EXE to start the evaluation program. When the program starts up a front panel window appears.
There exist five control items: MODE, Serial port No., Reference, SPEED and Average Index .
Further, there are a few indication items: RealReal- time value and Graphic chart of the measured
results, Std Deviation, Average value and Meas. time.
The UTI evaluation software allows the user to program and gather samples from the UTI evaluation
board via the serial port of the PC. The port number they wish to use is selected by using the item,
Serial port No .. The item MODE is used to select the mode of the UTI and SPEED to set the UTI in
a slow or a fast mode.
The item Reference is used to set the reference signal value corresponding to the value of a
reference capacitance or a reference resistance. For example, when the evaluation board is used to
measure the signal from a Pt100 and a reference resistor of 100.00 Ω is used, the item Reference
should be set to 100.00.
The item Average Index is used to set the number of measurements to be averaged. A large
number of measurements results in lower noise, but also increases the measurement time.
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
7/8
The output information
RealReal- time value digitally displays the measurement result. For instance, for the measurement of a
Pt100, the measured resistor value of the Pt100 is displayed, and for the measurement of the
potentiometer, the relative value is displayed.
Meanwhile, a graphic chart displays the real-time value by a red line.
The item Average Value indicates the average value of a variable number of measurements
indicated by the Average Index.
The item Std Deviation indicates the standard deviation of the evaluation board for a variable (by
Average Index) number of the measurements.
Table 1 lists the displayed measurement results for each UTI mode.
The item Meas. time indicates the measurement time for one complete measurement. F or
instance, to measure a capacitance by using mode C23 of UTI, the Meas. time is the total time to
measure the three periods, Toff, Tx and Tref (see UTI specification sheet).
To Start Measurement
Double clicking the button ⇒ at the top-left corner of the front-panel window will start the
measurement. After a few seconds the results are displayed at the monitor.
4.2 Terminal under Windows
The program Terminal (or Hyper terminal)
terminal under Windows can easily display the measurement
results via the serial port of the PC. The configuration of Terminal (or Hyper terminal)
terminal is: 8 data bit,
1 stop bit and No parity error check. The microcontroller will automatically select the baudrate by
sending a @ sign to the evaluation board. So, in order to have a communication between the
microcontroller and the PC, first the sign @ is send to the microcontroller.
Once the communication between the microcontroller and the PC is actuated, by typing “H”, “h” or
“?”, you can get on-line help. With this on-line help, it is easy to manage the evaluation board and to
display the result.
The displayed data under the Terminal (or Hyper terminal)
terminal is Hexadecimal. The data, which
corresponds to the time interval of each phase of the UTI output signal. Using the counting function
of the microcontroller, with a counting frequency of 5 MHz, the time intervals are measured
accurately.
5. OnOn- board reprogramming the microcontroller with the ICD
Together with the evaluation board also the microcontroller software is supplied. This software
enables the evaluation of the sixteen basic modes of the UTI. Yet, for specific applications, it is
possible that it is needed to modify the software. This is the case, for instance, when the UTI is used
in combination with an external multiplexer, to perform multiple-capacitance measurements (see
section 6). For easy on-board reprogramming of the microcontroller, the evaluation board provides
a 6-pad soldering array (J4 see Figure 5) to mount a six-pole connector for the ICD module (In Circuit
Debugger). This module is available from Microchip and can be ordered with Smartec. In order to
use the ICD, the microcontroller should have the ICD capability. For this option, for instance, the
PIC16F873 or PIC16F876 can be used.
last update
February 7, 2011
UTI Evaluation board
reference
uti toolkitn.doc
page
8/8
6. MultipleMultiple- capacitance
capacitance measurement
A large number of capacitances can be measured using the CMUX mode of the UTI together with an external
multiplexer, such as Smartec’s MUX03. The number of measured capacitances is not limited. For detailed
information on the MUX03, please consult the MUX03 specification sheet.
With a single external MUX03 the evaluation board provides the possibility to measure up to nine capacitances.
The evaluation board generates the three control signals (CLR, DATA and SCK) for the external multiplexer. When
the program Terminal (or Hyper terminal)
terminal under Windows is used to display the measurement results, after
sending the character ‘3’ for selection of the CMUX mode, a character between ‘1’ and ‘9’ (HEX 31 to 39) should
be sent to specify the number of capacitances to be measured. When this character is ignored, the system will
use the default value (‘9’), which means that nine capacitors are measured.
Attention:
Do not forget to switch on the power supply of the evaluation board before starting the measurement.
Mode
Result 1
Result 2
Result 3
0
(CDA-CBA)/(CCA-CBA)Cref
(CEA-CBA)/(CCA-CBA)Cref
(CFA-CBA)/(CCA-CBA)Cref
1
(CDA-CBA)/(CCA-CBA)Cref
×
×
2
(CDA-CBA)/(CCA-CBA)Cref
(CEA-CBA)/(CCA-CBA)Cref
(CFA-CBA)/(CCA-CBA)Cref
3
See section 6
4
(CDA-CBA)/(CCA-CBA)Cref
×
×
5
RCD/RABRref
RBC/RABRref
×
6
RCD/RABRref
RBC/RABRref
×
7
RCD/RABRref
RBC/RABRref
RDF/RABRref
8
RCD/RABRref
RBC/RABRref
RDF/RABRref
9
VCD/VAB
×
×
10
VCD/VAB
×
×
11
VCD/VAB
×
×
12
VCD/VAB
×
×
13
VCD/VEA
RAB/RBFRref
×
14
VCD/VEA
RAB/RBFRref
×
15
VBF/VEF
VCF/VEF
VDF/VEF
Note: ×: No measurement.
Table 1. The displayed measurement results for various modes._